Preheat Your Chimney Flue for Better Drafting

Basic physics keep the smoke flowing up your chimney rather than back into your home. During cold weather months, particularly if your chimney is located on an exterior wall, those physics can work against you, however. You may notice smoke drafting back into your home when you first light a fire. Preheating your chimney flue can help solve this problem and have your chimney working perfectly.

Why should you preheat your chimney?

When a fireplace and chimney are working properly, your fire draws in the cooler air from your home to fuel the fire. As the heat of the fire increases, the hot air rises out of your chimney, taking smoke and other fire byproducts with it. When it’s extremely cold, however, your chimney fills with cold outside air, particularly if it’s on an outside wall of your home. When cold air, which is denser and heavier than warm air, fills your chimney, the smoke can’t rise out of the firebox when you first light a fire. Preheating your chimney forces that cold air out, so that when you light your fire, the smoke will draft properly.

How do you preheat your flue?

There are several ways to preheat your chimney flue, but the easiest and most common is to roll four to five newspaper “torches” tightly and light them on fire in your fireplace. By the time those papers are burned, your flue should be warm enough to draft properly. You also can use a blow dryer or a fan to physically blow the cold air out of your flue. The blowing air doesn’t need to be hot, just warmer than the freezing air filling your flue.

How else can you help your chimney draft properly?

There are a few other simple steps you can take to keep smoke flowing up your chimney rather than back into your home. Crack open a window in the same room as your fireplace by one inch to help your fireplace draw in cold air. Make sure you’re building a hot enough fire. Use only dried, seasoned wood to build your fire, and build an appropriate size fire for you firebox ,but also make sure not to overload the firebox with wood,. Build fires in a metal grate off the floor of your firebox, and place wood as far back into the fireplace as possible. If you fireplace has glass doors, leave them fully opened when a fire is burning. Closing the doors prevents the chimney from drafting properly, creating a buildup of pressure that can crack the fireplace doors.

What should you do if smoke is still billowing into your home?

If you preheat your flue and follow our tips but still have smoke billowing into your home when you build a fire, there may be a larger problem at play. Your flue could be blocked, or improperly sized for your fireplace. If you’re constantly bothered by smoke entering your home rather than exiting your chimney, or if smoke is suddenly a problem from a chimney that has always worked well, call us at Clean Sweep of Anne Arundel County to examine your chimney for root of the drafting problem.